Ultrastrong and ductile NiFeCrAlV complex-concentrated alloy via dual-morphology brittle intermetallic compound

Abstract

Complex-concentrated alloys (CCAs) have received a lot of attention recently due to their exceptional balance between strength and ductility. In this work, a brittle intermetallic compound strengthening Ni46.3Fe21Cr18.5Al10V4.2 (at%) CCA has fabricated via carefully two-step thermomechanical treatment. The microstructure, phase composition, and mechanical properties of this alloy were investigated systematically. The microstructure characterization that brittle dual-morphology B2 particles are major second phases for the alloy under the two-step heat treatment. The microstructure characterization reveals that the coarse spherical B2 intermetallic compounds pinned grain boundaries and the dispersed dual-morphology B2 intermetallic compounds in the FCC matrix are key factors contributing to excellent mechanical properties. The yield strength and ultimate strength of the CCA enhanced substantially from 920 MPa and 1230 MPa in the annealed state, respectively, to 1400 MPa and 1660 MPa after aging treatment, while the uniform elongation remains above 18.5%. This work reveals the mechanical properties of the CCA can be enhanced by controlling B2 particles morphology and dispersion via suitable thermomechanical processing to meet the requirements of engineering applications.